Field of the Invention
The present invention relates to an image forming device that includes a fixing device including a heater, and a paper determining method of determining fed paper.
Description of the Related Art
In recent years, it becomes necessary for an image forming device to correspond to various kinds of paper due to diversification of media. Specifically, it is desired to correspond to paper with high smoothness such as coated paper or paper with extremely low smoothness such as rough paper. In order to correspond to these kinds of paper, it is necessary to set a parameter for each kind of paper and to control a printing operation. Thus, a unit of automatically detecting a kind of paper becomes necessary for an image forming device.
As an example, a technology of estimating electric energy consumed by a heater of a fixing device in an arbitrary period by measuring current flowing in the heater and voltage applied thereto, of detecting a kind of paper based on the power consumption, and of controlling a paper carrying interval or a lighting rate of the heater is known (see JP 11-133801 A). According to the technology described in JP 11-133801 A, it is possible to perform determination of a weight difference between pieces of paper and determination of rough paper or the like by measuring power consumption during continuous printing.
As a different example, a technology of determining a kind of paper from a temperature detected by a temperature sensor in a case where printing is performed in a prescribed on/off interval of a heater in the beginning of a job, setting a target fixation temperature according to the kind of paper, and controlling the heater to keep a fixation temperature of a fixing member at the target fixation temperature is known (see JP 2006-23329 A). According to the technology described in JP 2006-23329 A, it is possible to perform printing in a prescribed on/off interval of a heater in the beginning of the printing and to detect grammage of paper based on a temperature detected by a temperature sensor.
As a different example, a technology of determining a printing condition (plain paper mode or gloss mode) based on a kind of paper detected by utilization of an LED and a sensor and a printing rate calculated by a printing rate calculation unit is known (see JP 2009-8778 A). According to the technology described in JP 2009-8778 A, a transmittance and glossiness of paper are measured with an LED and a sensor and detection of grammage of paper and detection of coated paper or the like are performed.
However, in the technology described in JP 11-133801 A, power consumption varies depending on a state of a fixing device during continuous printing. Thus, it is difficult to determine a kind of paper accurately. Further, a unit of measuring current and voltage is necessary and a cost is increased.
In the technology described in JP 2006-23329 A, it is not possible to determine how much a fixing member is warmed and to determine a state of a power supply. Thus, it is not possible to determine grammage of paper accurately. In addition, in the technology described in JP 2006-23329 A, smoothness of paper is not detected.
In the technology described in JP 2009-8778 A, a kind of paper is detected based on a transmittance and glossiness. Thus, it is difficult to perform a detailed detection such as detection of a basis weight difference in thick paper or detection of rough paper. In addition, since it is necessary to provide an LED and a sensor, a cost is increased.